Brown-headed cowbird (Molothrus ater) is mostly known for its brood parasitism. Unlike other birds they don't construct their own nest, instead they lay their eggs in that of smaller birds. By doing this they are able to reproduce much quicker because they don't have to "babysit" each egg.
height: 7 inches weight: 1 to 1.75 ounces
Detailed Description
The brown-headed cowbird is an authentic Yankee. A habitual gender bias on the part of people who name birds is reflected in the fact that only the male has a brown head, which contrasts with its iridescent black body. The females are grayish-brown, the young birds paler and more heavily streaked. Both sexes have a stubby bill.
Diet: Corn; wheat; oats; grasses; seeds; soft mast such as black cherries, blackberries and wild grapes; and invertebrates including grasshoppers, beetles, caterpillars and other insects, land snails and spiders.
The cowbird chicks hatch early than other birds and they are larger and more aggressive and will out-compete their nest mates for food.
Reproduction
The egg is whitish or bluish-white, darkly speckled, and thick-shelled--so it can withstand rough handling if a suspicious host tries to eject it from her nest. Although cowbird eggs are usually larger than those laid by the host, they are designed to hatch quickly and thus give the chick a jump in the race for survival. According to a 1995 report in the ornithology journal The Auk by Colombian biologist Gustavo Kattan, who has studied shiny cowbirds. The chick simply runs out of yolk, which sends it a signal: "It's time to get out of here!" The chick hatches and begins clamoring for food before the legitimate nestlings are up and begging. It scarcely matters that the cowbird "preemie" is scrawny, because the small host produces small chicks.
Habitat & Distribution
The center of the family's distribution is South America and it has spread throughout the United States and Southern Canada. It adapts to its climate allowing it to reproduce in other areas and expand its population.
The cowbird affects the living of other birds because of its brood parasitism. By the cowbird laying eggs in the nest of other birds, the other eggs do not receive as much nourishment due to the fact that the cowbird hatches early and is bigger then the other species. Since the population of the cowbird increased, we have been seeing a decrease in the population of other song birds.
History
The brown-headedcowbird coevolved on the Great Plains with the omnipresent bison; early settlers called it the buffalo bird. But the slaughter of the American bison changed this bird's life. It switched to the domestic cattle that replaced the bison, became a "cowbird" and expanded its range throughout the continental United States and southern Canada.
Control Measures
To control the population and the threat of the cowbird traps are set up. Female cowbirds are killed once they are caught, however some males are set free so their location and movements can be tracked. (5)
Brown-headed cowbird (Molothrus ater)
General Information
Brown-headed cowbird (Molothrus ater) is mostly known for its brood parasitism. Unlike other birds they don't construct their own nest, instead they lay their eggs in that of smaller birds. By doing this they are able to reproduce much quicker because they don't have to "babysit" each egg.
height: 7 inches
weight: 1 to 1.75 ounces
Detailed Description
The brown-headed cowbird is an authentic Yankee. A habitual gender bias on the part of people who name birds is reflected in the fact that only the male has a brown head, which contrasts with its iridescent black body. The females are grayish-brown, the young birds paler and more heavily streaked. Both sexes have a stubby bill.Diet: Corn; wheat; oats; grasses; seeds; soft mast such as black cherries, blackberries and wild grapes; and invertebrates including grasshoppers, beetles, caterpillars and other insects, land snails and spiders.
The cowbird chicks hatch early than other birds and they are larger and more aggressive and will out-compete their nest mates for food.
Reproduction
The egg is whitish or bluish-white, darkly speckled, and thick-shelled--so it can withstand rough handling if a suspicious host tries to eject it from her nest. Although cowbird eggs are usually larger than those laid by the host, they are designed to hatch quickly and thus give the chick a jump in the race for survival. According to a 1995 report in the ornithology journal The Auk by Colombian biologist Gustavo Kattan, who has studied shiny cowbirds. The chick simply runs out of yolk, which sends it a signal: "It's time to get out of here!" The chick hatches and begins clamoring for food before the legitimate nestlings are up and begging. It scarcely matters that the cowbird "preemie" is scrawny, because the small host produces small chicks.Habitat & Distribution
The center of the family's distribution is South America and it has spread throughout the United States and Southern Canada. It adapts to its climate allowing it to reproduce in other areas and expand its population.Habitat: Farmland, grassland, forest edge, deciduous woodland
Impact
- Ecological Impacts
The cowbird affects the living of other birds because of its brood parasitism. By the cowbird laying eggs in the nest of other birds, the other eggs do not receive as much nourishment due to the fact that the cowbird hatches early and is bigger then the other species. Since the population of the cowbird increased, we have been seeing a decrease in the population of other song birds.History
The brown-headed cowbird coevolved on the Great Plains with the omnipresent bison; early settlers called it the buffalo bird. But the slaughter of the American bison changed this bird's life. It switched to the domestic cattle that replaced the bison, became a "cowbird" and expanded its range throughout the continental United States and southern Canada.Control Measures
To control the population and the threat of the cowbird traps are set up. Female cowbirds are killed once they are caught, however some males are set free so their location and movements can be tracked. (5)
References
1. LOWTHER, PETER E. "RESEARCH AND MANAGEMENT OF THE BROWN-HEADED COWBIRD IN WESTERN LANDSCAPES.(Review)." Wilson Bulletin. 112. 2 (June 2000): 298. Student Resource Center - Gold. Gale. Stroudsburg High School. 13 Nov. 2008 http://find.galegroup.com/srcx/infomark.do? &contentSet=IAC-Documents &type=retrieve &tabID=T002 &prodId=SRC-1 &docId=A63789290 &source=gale &srcprod=SRCG &userGroupName=stro53037 &version=1.02. Graham, Frank Jr. "Bad, bad birds: the cowbird's habit of intruding on the nests of other birds obscures a marvel of evolution." Audubon. v100. n5 (Sept-Oct 1998): p104(4). Student Resource Center - Gold. Gale. Stroudsburg High School. 13 Nov. 2008 http://find.galegroup.com/srcx/infomark.do? &contentSet=IAC-Documents &type=retrieve &tabID=T003 &prodId=SRC-1 &docId=A21207096 &source=gale &srcprod=SRCG &userGroupName=stro53037 &version=1.0
3. Dunaief, Daniel. "Taking back the nest; as cowbirds push some songbirds toward extinction, conservationists are debating an uncomfortable solution: killing the pests." Discover. v16. n5 (May 1995): p34(1). Student Resource Center - Gold. Gale. Stroudsburg High School. 13 Nov. 2008 http://find.galegroup.com/srcx/infomark.do? &contentSet=IAC-Documents &type=retrieve &tabID=T003 &prodId=SRC-1 &docId=A16914790 &source=gale &srcprod=SRCG &userGroupName=stro53037 &version=1.0
4. http://www.michigan.gov/dnr/0,1607,7-153-10370_12145_12202-60308--,00.html
5. www.tpwd.state.tx.us/publications/pwdpubs/media/pwd_bk_w7000_1148. pdf
6. http://ct.gov/DEP/cwp/view.asp?a=2723&q=325990&depNav_GID=1655